Small Hole in Tank

[Paul75]

Thanks Marlen. Is panel bond adhesive similar to JB Weld? Definitely agree about the welding, I've viewed hours of youtube videos now and have decided on a gas MIG. I was planning on using my dremmel to cut out a small rectangular hole in the tank, then cut the same gauge steel sheet slightly larger, but overlap on the surface but thinking about it I could, like you say, slide this inside, hold with magnets and weld inplace. I will look into the panel bond adhesive too but I think I'll weld it mainly for a perfect seal and also because I don't want to risk any 'gassing' coming off and wrecking the finished paintwork.

Paul

 

[Bob Kelly III]

keep in mind welding thin sheet metal is the hardest welding to do of any of the metals ! you are likely to just blow holes into the sheet metal as to weld it..... on one hand you have the amperage that makes it easier to strike an arc with a stick welder... on the other the more amps you use it will melt away the metal as fast as the arc strikes..... when your sheet metal is about the thickness as your welding rod you start having these problems
weather it's wirefeed welding or stick welding ... how ever ox/acetiline welding is a bit diferent... there you heat the metal with the torch and apply welding rod..... the problem is if you heat it to molten it just melts a big hole in the sheet metal.... this is why braseing is so much better
all brasing is is real high heat solder it's not nessarry to get the metal white hot...just red hot will do or even just close to that....
if your planning to weld the gastank then practice on metal the same thickness as the gastank..... a coupple of big sheets cut into small 5" squares and weld them all together then drill a hole in 4 or 5 and try to patch that hole with a plate on the back side.....
it is far mor dificult than it sounds ! .... thin metal is extreamily hard to weld it is usually Spot welded by manifacturers insted of seam welded because of that. seam welding is far easier than Patch welding because it's easier to control the tempiture of the metal on the outside edge..... and this is with an Oxigen/Accetiline torch..... not a electric rig... their ten times harder to weld thin metal with !.... mainly because they were not designed to do it.
if you attempt to MIG weld a gastank get the peoperly sized wire for the wire feed or don't even bother ! it's that critical. and it's hard to find smaller wire to weld with..... half the time it's just not available.... they want to sell you 22guage wire but you may need something half that size !
...... I say brase it..... and fill with filler when done.....
a small ox/aset. welding outfit can be had fairly cheaply and is all you need however the gas don't last very long in those tiny cylinders like 10 min. max
and your OX will run out first. ..... so buy extra !
Good luck !
Bob..........

 

[weaselbeak]

I don't think it's that tough to seal a fuel tank with a small leak. Gasoline is thin, but there ain't sh*t for pressure in there. We used to seal gas tanks on old cars with Bondo. My son quick like made an ugly tank for his little Moto Guzzi so he could carry more fuel on a road trip to Canada & it was a stretch between stations on a couple of legs. When he finished trying to weld everything he had about 9 pinhole type leaks, some pretty bad. He was just learning to weld, so no surprise. We worked JB Weld down the seams as well as possible and Red-Koted it twice. It's never leaked and is still on the bike, 2 years later. I would have just used Bondo to start with but my can was so old it was dried up.

 

[YamadudeXS650C]

Bob Kelly has offered a very coherent set of reasons to braze if you are going that route (vs. epoxy). You can buy a small amount of brazing rods with flux covering, all ready to go. If you aren't an old fart like me and some others who have some years on us, you might not have an oxy-acetylene set-up (I got mine in the 60's when I was a teenager), but you can buy a small can of Mapp gas and screw it into your hi-velocity propane torch (cheap), and it will give you temps to braze effectively. BTW, welding safety glasses are needed for brazing, despite the lower temps.

 

[Bob Kelly III]

there ya go !!! !!!! that works ! I've used Mapp gas before and it works great to brase with ! !!!!
....
Bob......
i remember doing a big brasing job one time that used up a hand full of brazing rod...
I just used my dark sunglasses.... I was seeing spots the next 2 days ! Don't do as I did !

 

[fredintoon]

Hi Paul,
while I'd never tell anyone NOT to buy a welding machine I don't reckon welding is the best choice to DIY fix that rust-rotted gas tank.
What I'd do is cut the rusted area out to good metal, wire brush a thumbswidth all around the cut-out to a bright finish,
hammer up an oversized patch of same gauge sheet steel and pop-rivet it onto the tank.
Then use a propane torch, soft solder and paste flux to seal it all up.
And forget trying to save the paint job, ANY kind of heating will wreck at least the rear third of it.

 

[Paul75]

Cheers Fred, I know what you mean about not welding it up....I'm not too sure about pop-rivets though. Paint job, I'm not worried about the current paint, far from it, I just don't want gassing coming up from JB Weld (I read this can happen somewhere) etc, I know all too well what its like to get a great paint job going only for it it be wrecked by a non-inert product underneath!!

 

[fredintoon]

Cheers Fred, I know what you mean about not welding it up....I'm not too sure about pop-rivets though. Paint job, I'm not worried about the current paint, far from it, I just don't want gassing coming up from JB Weld (I read this can happen somewhere) etc, I know all too well what its like to get a great paint job going only for it it be wrecked by a non-inert product underneath!!

Hi Paul,
what's wrong with pop-rivets? What do you think holds aircraft together?
You can use blind-ended pop-rivets if you are concerned about sealing their centres with solder.
And yes, plastic and fuel don't get along too well. I once used epoxy to fix a tank that had been Vandalised
so badly that some of the dents in the top had split open. Took a few years but the petrol fumes finally lifted blisters in the epoxy.

 

[Paul75]

Guys just an update, I had the tank tig welded. A plate was placed inside the tank and then welded up, no leaks from water so all good. Off for paint tomorrow!

 

[Bob Kelly III]

cool ! glad you got it done ! now make it purdy ! LOL
....
Bob..........